This invention is directed to an engine cooling system and particularly to a means for venting air during filling.
Currently, in engine cooling systems it is frequently the practice to provide an orifice between a first chamber of the thermostat housing which communicates with the engine and a second chamber of the thermostat housing which communicates with the engine. The purpose of providing this orifice is to allow entrained air in the cooling system fluid to vent when the thermostat is closed and the system is being filled. To a certain extent, the time required to fill the cooling system is dependent on the rate at which air escapes through the orifice, the radiator top tank and thence to atmosphere.
Use of a fixed orifice has not been entirely satisfactory since a small amount of coolant continues to circulate to the radiator even when the engine is cold by bypassing the closed thermostat. This unwanted circulation occurs, for example, during cold weather operation and causes the engine to continue to run cold, which is detrimental to engine operation.
To somewhat alleviate this problem, it has been the practice to provide movable shutters on vehicles having such a fixed orifice vent in order to prevent cold outside air from reaching the engine compartment. While the use of movable shutters is effective, they create an undesirably high level of noise when closed.